1. Field of the Invention
This invention relates to an automatic tools changing apparatus for a vertical type multi-spindle machine tool, with four or more spindles, which is capable of changing tools for plural spindles simultaneously.
2. Description of Prior Art
Heretofore, there have been proposed various effective automatic tools changing methods and apparatuses for single-spindle machine tools which are capable of carrying out an automatic tools changing operation easily and effectively, because tools may be changed one by one in such single-spindle machine tools.
However, there have not yet been known effective methods and apparatuses for carrying out an automatic tools changing operation for vertical type multi-spindle machine tools with four or more spindles. Therefore, an automatic tools changing operation for a multi-spindle tool is carried out in such a manner that a plurality of automatic tools changing apparatuses for a single-spindle machine tool are employed for the respective spindles of the multi-spindle machine tools or a tool magazine adapted to move for carrying out the tool changing between the tool magazine and spindles without using a tool-changing arm is employed when the number of the tools is as small as two or three.
However, the former method in which a plurality of automatic tools changing apparatuses for a single-spindle machine tool are provided has such a disadvantage that it is difficult to mount more than two tools changing apparatuses on one tool machine due to problems of a mounting space and interference caused between the apparatuses and it cannot be expected to significantly reduce a time required for a tools changing operation. The latter method in which tools are changed between the spindles and the tool magazine has such a disadvantage that the arrangement of the machine tool is highly restricted by the tool magazine which should be moved relative to the spindles and it is difficult to be applied to a machine tool having four or more spindles.